ANALYSIS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY

Laboratory Service Veterans Affairs Medical Center 3350 La Jolla Village Drive San Diego, California 92161 and Department of Pathology University of CaliforniaSan Diego La Jolla, California 92037, USA 

Department of Pathology University of Virginia Charlottesville. Virginia 22908, USA 

A variety of techniques based on different physical principles have been used for trace element measurements. The most commonly used include neutron activation analysis (NAA) [1], atomic absorption spectrometry [2,3], and mass spectrometry [4-7]. The two distinct advantages primarily responsible for the selection of NAA in earlier studies appeared to be the option to determine several trace elements simultaneously and the elimination of complex chemical separation steps. The poor precision values obtained by NAA have recently necessitated prechemical separation, which introduces problems of analyte loss, contamination, and blank correction. However, the major drawbacks are the requirement of a nuclear reactor facility, the slow turnaround of the samples, and the relatively high cost of analysis. Nonetheless, NAA is a well-established, multielemental, nondestructive technique with detection limits for most elements in the 1-50 p.g/liter range. This topic is covered by Heydom in Chap. 13 of this book. 

Electrothermal atomic absorption spectrometry (ETAAS) has also been used for the determination of trace elements in biological samples because of its speed, minimum need for sample preparation, possibility of automation, and good sensitivity. However, ETAAS measurements are susceptible to matrix effects and therefore require standards similar to the samples. In addition. 

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Analysis of pesticides (eight in total, namely, molinate, propanil, fenitrothion, malathion, bentazone, cypermetrine, maloxon, and fenitrothion oxon) in biota was accomplished with a method based on pressurized liquid extraction (ASE), followed by SPE clean-up, and analysis by gas chromatography-mass spectrometry with electron impact ionization (GC/MS-EI). 

In order to understand the removal of FMs during wastewater treatment, it is necessary to measure these compounds throughout the wastewater treatment process. Because of the complex nature of wastewater matrices and the low concentration of FMs (0.001-60 pg/L) [11] throughout the treatment plant, accurate and sensitive analytical methods have been developed by a number of researchers. Fortunately, the analytical techniques developed to measure traditional SOCs, such as solvent extraction, extract concentration, and analysis by gas chromatography-mass spectrometry, in general also apply to FMs. 

Cyperquat, a post-emergence herbicide has been determined in surface soil by a method involving catalytic hydrogenation to l-methyl-4-cyclohexypiperdine and analysis by gas chromatography-mass spectrometry. Recovery of cyperquat from fortified soil samples was 77% at the 0.5mg kgy1 level and 85% at the lmg kgy1 level [213]. 

Blomberg, L., and G. Widmark. Separation of fresh tobacco smoke on a packed polar gas chromatographic column prior to on-line analysis by gas chromatography-mass spectrometry using a non-polar capillary column. J Chromatogr 1975 106 59. 

McCaffrey, C. A., J. MacLachlan, and B. I. Brookes, Adsorbent Tube Evaluation for the Preconcentration of Volatile Organic Compounds in Air for Analysis by Gas Chromatography-Mass Spectrometry, Analyst, 119, 897-902 (1994). 

Dasgupta, A., Banerjee, P. and Malik, S., Use of microwave irradiation for rapid transesterification of lipids and accelerated synthesis of fatty acyl pyrrolidides for analysis by gas chromatography-mass spectrometry study of fatty acid profiles of olive oil, evening primrose oil, fish oils and phospholipids from mango pulp,... 

Bianchi et al. [134] and Yokouchi and Sano [135] obtained good recoveries of volatile organic compounds in soils employing thermal vaporisation followed by trapping on Tenax GC and analysis by gas chromatography-mass spectrometry. 

Solutions of triethylamine (Et3N) 14 (1.0M), premixed carboxylic acid/alkyl chloroformate (1.0 M respectively), and 4-dimethylaminopyri-dine 15 (0.5 M) in MeCN were introduced into the reactor from separate inlets and the reaction products collected at the outlet in MeCN, prior to analysis by gas chromatography-mass spectrometry (GC-MS). Under optimized reaction conditions, the authors were able to synthesize the methyl 16, ethyl 17, and benzyl 18 esters in quantitative conversion, with no anhydride or deprotection by-products detected (as observed in conventional batch reactions). In addition to the Boc-glycine derivatives illustrated in Scheme 4, the authors also esterified a series of aromatic carboxylic acids with yields ranging from 91 to 100%, depending on the additional functional groups present. 

Hook, G. L., Kimm, G. L Hall, T and Smith, P. A. (2002). Solid-phase microextraction (SPME) for rapid field sampling and analysis by gas chromatography-mass spectrometry (GC-MS). Trends Anal. Chem. 21, 534-543. 

Chemical Analysis by Gas Chromatography-Mass Spectrometry GC-MS. Volatiles isolated from the oils were separated by GC. A Girdel Series 300 instrument equipped with a FID detector was used for quantification. Column DB Wax, 0.32 mm id x 25 m. Carrier gas hydrogen with a flow rate of 3 ml/min. Column temperature programmed, 40-220°C at a rate of 3°C/min. The extract was injected, with split, onto the column. 

Acute transient urinary retention associated with metamfetamine and ecstasy (3,4 methylenedioxymetamfeta-mine, MDMA) in an 18-year-old man has been described (76). Analysis by gas chromatography-mass spectrometry confirmed the presence of metamfetamine (>25 pg/ml), MDMA (> 5 pg/ml), amfetamine (1.4 pg/ml), and methylenedioxyamfetamine (3.7 pg/ml) in the urine. Bladder dysfunction resulting from alpha-adrenergic stimulation of the bladder neck may have explained the observed effect. 

Patterson, B. W., Carraro, F., and Wolfe, R. R. (1993). Measurement ofenrichment in multiple amino acids and urea in a single analysis by gas chromatography/mass spectrometry. Biol. Mass Spectrom. 22. 

To further complicate the picture, chemical additives are often not pure compounds but mixtures of related structures. The name or chemical designation of the additive often represents only the primary or most abundant chemical structure present. For example. Fig. 1 shows a chromatogram from the analysis by gas chromatography/mass spectrometry (GC/MS) of Abietic Acid, which is an organic chemical filler used in certain types of rubber. The molecular structure of Abietic Acid (I) is ... 

Analysis by gas chromatography-mass spectrometry (GC/MS) using selected ion monitoring is the reference method, Methods for trazodone and amoxapine are also available. HPLC has been successfully used for analysis of tricyclic antidepressants, although separation and selectivity are problems with this technique. ... 

To address whether O2 is involved in f-BuOOH epoxidation by a radical pathway, the corresponding labeling experiments were conducted. The product analysis by gas chromatography-mass spectrometry shows substantial incorporation of from O2 into norbomylene oxide (74.6 2% incorporation vs... 

An herbicide, atrazine, which is commonly used on corn crops in the mid-western United States, was chosen as an example. During the spring, rainfall washes this compound from soil, and concentrations of herbicide in surface water will reach the Environmental Protection Agency s annual maximum contaminant level of 3 gg/L. It is necessary to detect this compound at concentrations as low as 0.05 gg/L. How would one isolate and purify this compound from water for analysis by gas chromatography/mass spectrometry (GC/MS) using SPE Some questions and ideas that come to mind follow ... 

Brooks, K. E. and Smith, N. B. 1991. Efficient extraction of basic, neutral, and weakly acidic drugs from plasma for analysis by gas chromatography-mass spectrometry, Clin. Chem.,31 1975-1978. 

D.A. Herold, S.K. Aggarwal and M. Kinter, Trace metal analysis by gas chromatography/mass spectrometry a less-invasive analytical technique. Clin. Chem. 38, 1647-1649 (1992). 

Reverchon E, Senatore F. Supercritical carbon dioxide extraction of chamomile essential oil and its analysis by gas chromatography-mass spectrometry. J Agric Food Chem 1994 42 154-158. 

HL Hubbard, TD Eller, DE Mais, et al. Extraction of thromboxane B2 from urine using an immobilized antibody column for subsequent analysis by gas chromatography-mass spectrometry. Prostaglandins 33 149, 1987. 

Ng, L. K., Analysis by gas chromatography/mass spectrometry of fatty acids and esters in alcoholic beverages and tobaccos. Anal. Chim. Acta, 465, 309-318, 2002. 

In this paper, we have compared two commonly used permethylation methods [4, 5] and have applied them to a model carbohydrate compound. The completeness of the methylation steps was established by matrix-assisted laser desorption/ionization tlme-of-flight mass spectrometry (MALDI-TOF MS). The methylated carbohydrate products were acid-hydrolyzed and converted to methylated partially acelylated aldononitrile derivatives (Me PAANs) for linkage analysis by gas chromatography-mass spectrometry (GC-MS) [11]. 

Thomas, C.L.P. McGill, C.D. Towdl, R., Determination of formaldehyde by conversion to hexahydrooxazolo[3,4-a]pyridine in a denuder tube with recovery by thermal desorption, and analysis by gas chromatography-mass spectrometry, Ano/yjf 1997,122,1471-1476. 

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